1. Field of the Invention
The present invention is generally in the field of electronic circuits and systems. More specifically, the present invention is in the field of communications circuits and systems.
2. Background Art
Transceivers are typically used in communications systems to support transmission and reception of communications signals through a common antenna, for example at radio frequency (RF) in a cellular telephone or other mobile communication device. Although transmission and reception of communication signals may occur at RF, signal processing is typically performed at a lower frequency, such as at baseband, after down-conversion of a receive signal or prior to up-conversion of a transmit signal. Frequency conversion, either up-conversion or down-conversion, is usually performed by respective transmitter or receiver mixers included in the transceiver, which are in turn driven by local oscillator generator (LOGEN) circuits of the transceiver.
In a LOGEN circuit, the output of a voltage controlled oscillator (VCO) may be buffered and adjusted in frequency one or more times before being provided to drive one of the transmitter or receiver mixers of the transceiver. Because drive strength and low phase noise are important in LOGEN performance characteristics, conventional LOGEN circuits are powered so as to meet specifications for those parameters even under the most unfavorable conditions, which may only occasionally prevail. As a result, a conventional LOGEN may be designed and consistently powered to enable it to satisfy its phase noise and drive strength specifications for slow process corners at high temperature. However, the power consumption needed to satisfy the LOGEN performance requirements under those worst case conditions is greater than that needed for normal, and especially for favorable, conditions, e.g., typical and fast process corners, resulting in unnecessarily high power consumption by the transceiver during much of LOGEN circuit operation. In addition, the power consumption of the digital circuits, like digital LOGEN circuits, is proportional to the square of the supply voltage. The lower the supply voltage, the less power is consumed.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing an adaptively powered LOGEN circuit suitable for implementation as part of a more modern mobile device transceiver and enabling reduced power consumption by the transceiver.